You'll have a bundle (which we call "Legendary") with basic BB2 + a pack with WE/LM/Nurgle/Norse/Necro/Undead/CD/Khemri + the "Legendary upgrade" at the price of a full game.
You'll also be able to buy only the "Legendary upgrade" if you already own BB2, with a big discount (we aim around 20€).
A pack with WE/LM/Nurgle/Norse/Necro/Undead/CD/Khemri for approximately 20€ will also be available before the release of Legendary.
Finally you'll still be able to get individual races if you wish.
I'll post all the details in an official announcement tomorrow. But the idea is that if you only get the "Legendary upgrade", CD and Khemri won't be in it.
Summer 2017, but it could be delayed depending on how the testing goes. We have a lot of complicated features requiring a lot of tests (rez mode for example) and we prefer to delay by a few months rather than have a messy release.